No abstract

Abstract. Melting method for synthesizing BC x N compounds has been improved, where the starting material is a mixture containing C and BN and wholly melted without reacting the container wall. Product is composed of two phases of BC x N compounds. Their structures are cleared to be of the hBN-type and of the graphite-type, respectively. Variation of lattice parameters of the both phases and their formation ratio are investigated in relation to the composition of the starting mixture. Existence of ordered arrangement of B, C and N atoms is suggested, too. A structure model is given for the phase of the hBN-type. IntroductionCompounds having composition of BC x N have been usually produced by the CVD method and considered to be intermediate compounds between C and BN having the structure of stacked hexagonal network planes, like graphite or hBN [1,2]. Some trials have been carried out to use them as the starting material for synthesizing hard solid solutions between diamond and cBN using very high pressure [3]. Some models are proposed for the atom arrangement of B, C and N within the network plane for the BC x N materials synthesized by CVD [2]. However, those materials are very poorly crystallized and discussion about the atom arrangement in the plane is very difficult on the basis of diffraction. The stacking structure of the planes is considered as being turbostratic.In the preliminary work of our study [4], we synthesized similar materials from graphite and hBN by melting them together at very high temperature. In the present study, we have refined the synthesis method, and carried out more detailed characterization of the product. We synthesize the materials by melting graphite in an hBN case, or powder mixture containing C and BN in an hBN case, the sample being confined in a high pressure space of a cubic anvil apparatus. The products are composed of very well-crystallized particles of two phases, each showing very sharp, almost ideal x-ray diffraction patterns. We are trying to characterize structural features of the products, including the atom arrangements in the hexagonal network planes.